Pots and pans with inserts which tilt have been around for many, many years. As an example, pots to boil pasta frequently have a strainer insert which is lifted out of the pot and then tilted and rested on top of the pot to allow the pasta to drain excess water. Deep fat fryers provide yet another example where a screen or sheet metal insert is lifted out of the boiling oil and rested in a tilted position on top of the pot to allow the fried food in the insert to drain.
The problem with previous designs is that their inserts may be unstable when tilted and rested on top of the pot and thus they may accidentally drop back into the pot with the risk of splashing hot liquid.